905458-54-0Relevant academic research and scientific papers
Catalytic Enantio- and Diastereoselective Mannich Addition of TosMIC to Ketimines
Franchino, Allegra,Chapman, Jack,Funes-Ardoiz, Ignacio,Paton, Robert S.,Dixon, Darren J.
, p. 17660 - 17664 (2018/11/10)
Chiral amines bearing a stereocenter in the α position are ubiquitous compounds with many applications in the pharmaceutical and agrochemical sectors, as well as in catalysis. Catalytic asymmetric Mannich additions represent a valuable method to access such compounds in enantioenriched form. This work reports the first enantio- and diastereoselective addition of commercially available p-toluenesulfonylmethyl isocyanide (TosMIC) to ketimines, affording 2-imidazolines bearing two contiguous stereocenters, one of which is fully-substituted, with high yields and excellent stereocontrol. The reaction, catalyzed by silver oxide and a dihydroquinine-derived N,P-ligand, is broad in scope, operationally simple, and scalable. Derivatization of the products provides enantioenriched vicinal diamines, precursors to NHC ligands and sp3-rich heterocyclic scaffolds. Computations are used to understand catalysis and rationalize stereoselectivity.
Bifunctional Iminophosphorane Catalyzed Enantioselective Ketimine Phospha-Mannich Reaction
Robertson, Gerard P.,Farley, Alistair J. M.,Dixon, Darren J.
, p. 21 - 24 (2015/12/26)
The enantioselective phospha-Mannich reaction of diethyl phosphite to unactivated N-DPP-protected ketimines catalyzed by a bifunctional iminophosphorane (BIMP) superbase organocatalyst is described. The reaction is applicable to ketimines bearing electron
Enantioselective Hydrosilylation of Imines Catalyzed by Chiral Zinc Acetate Complexes
Bez?ada, Agata,Szewczyk, Marcin,Mlynarski, Jacek
, p. 336 - 342 (2016/01/15)
A series of zinc acetate complexes with optically pure diphenylethanediamine (DPEDA)-derived ligands have been employed as enantioselective catalyst for the hydrosilylation of various imines. High control of stereoselectivity (up to 97% ee) and excellent yields (up to 96%) were gained for a broad range of N-phosphinoylimines by using (R,R)-N,N′-dibenzyl-1,2-diphenylethane-1,2-diamine. This is the first successful application of an air-stable and environmentally friendly chiral Zn(OAc)2 complex instead of the previously used harmful diethylzinc in the asymmetric reduction of the C=N double bond.
Direct catalytic enantio- and diastereoselective Mannich reaction of isocyanoacetates and ketimines
Ortin, Irene,Dixon, Darren J.
, p. 3462 - 3465 (2014/04/03)
A catalytic asymmetric synthesis of imidazolines with a fully substituted β-carbon atom by a Mannich-type addition/cyclization reaction of isocyanoacetate pronucleophiles and N-diphenylphosphinoyl ketimines has been developed. When a combination of a cinchona-derived aminophosphine precatalyst and silver oxide was employed as a binary catalyst system, good reactivity, high diastereoselectivities (up to 99:1 d.r.), and excellent enantioselectivities (up to 99 % ee) were obtained for a range of substrates. Binary catalyst system: A catalytic asymmetric synthesis of imidazolines with a fully substituted β-carbon atom through a Mannich-type addition/cyclization reaction of isocyanoacetate pronucleophiles and N-diphenylphosphinoyl ketimines has been developed. By employing a cinchona-derived aminophosphine precatalyst and silver oxide as a binary catalyst system, good reactivity and high diastereo- and enantioselectivities were obtained.
Creation through immobilization: A new family of high performance heterogeneous bifunctional iminophosphorane (BIMP) superbase organocatalysts
Goldys, Anna M.,Nez, Marta G.,Dixon, Darren J.
, p. 6294 - 6297 (2015/02/05)
An immobilized chiral bifunctional iminophosphorane superbase organocatalyst has been developed and applied in a range of challenging enantioselective reactions. A unique feature of this novel catalytic system is that the final step creation of the iminophosphorane occurs at the point of immobilization. The utility of the immobilized catalyst system was demonstrated in the nitro-Mannich reaction of ketimines as well as the conjugate addition of high pKa 1,3-dicarbonyl pro-nucleophiles to nitrostyrene. Catalyst recycling was also demonstrated.
